Statistical analysis
IBM SPSS statistics package was used for statistical analysis. Numerical data were tested for normality using the Shapiro-Wilk test. Numerical variables were expressed as mean ± standard deviation. Categorical variables were expressed in percentages. Paired and unpaired t tests were used when appropriate. Categorical variables were compared between groups by using chi square test. The significance level was defined as p< 0.05. To evaluate interobserver concordance, the intraclass correlation coefficient was calculated.